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981.
A new fluorescent probe L based on the rhodamine 6G platforms for Fe3+ has been designed and
synthesised. L showed excellent selectivity and high sensitivity for Fe3+ against other metal ions such as K+, Na+, Ag+, Cu2+, Co2+, Mg2+, Cd2+, Ni2+, Zn2+, Fe2+, Hg2+, Ce3+ and Y3+ in HEPES buffer (10 mM, pH 7.4)/CH3CN (40:60, V/V). The distinct color change and the rapid emergence of fluorescence emission provided naked-eyes detection for Fe3+. The recognition mechanism of the probe toward Fe3+ was evaluated by Job’s plots, IR and ESI-MS. In order to further study their fluorescent properties, L + Fe3+ fluorescence lifetime was also measured. Moreover, the test strip results showed that these probes could act as a convenient and efficient Fe3+ test kit. 相似文献
982.
Interlaminar Crack Propagation Analysis of ENF Specimens Based on the Cohesive Zone Model北大核心CSCD 下载免费PDF全文
Based on the classical laminated plate theory and the cohesive zone model, a theoretical model for general delamination cracked laminates was established for crack propagation of pure mode Ⅱ ENF specimens. Compared with the conventional beam theory, the proposed model fully considered the softening process of the cohesive zone and introduced the nonlinear behavior of ENF specimens before failure. The predicted failure load is smaller than that under the beam theory and closer to the experimental data in literatures. Compared with the beam theory with only fracture toughness considered, the proposed model can simultaneously analyze the influences of the interface strength, the fracture toughness and the initial interface stiffness on the load-displacement curves in ENF tests. The results show that, the interface strength mainly affects the mechanical behavior of specimens before failure, but has no influence on crack propagation. The fracture toughness is the main parameter affecting crack propagation, and the initial interface stiffness only affects the linear elastic loading stage. The cohesive zone length increases with the fracture toughness and decreases with the interface strength. The effect of the interface strength on the cohesive zone length is more obvious than that of the fracture toughness. When the adhesive zone tip reaches the half length of the specimen, the adhesive zone length will decrease to a certain extent. Copyright ©2022 Applied Mathematics and Mechanics. All rights reserved. 相似文献
983.
Let and A sequence is obtained by the formula The sequence is a sequence of pseudorandom numbers of the maximal period length if and only if (mod 4), (mod 4). In this note, the uniformity is investigated by the 2-dimensional serial test for the sequence. We follow closely the method of papers by Eichenauer-Herrmann and Niederreiter.
984.
John Schmeelk 《Foundations of Physics Letters》1990,3(5):403-423
Laurent Schwartz, the principle architect of distribution theory, presented the impossibility of extending a form of multiplication to distribution theory. There have been many varieties of partial solutions to this problem. Some of the solutions contain heuristic computations done by physicists in quantum field theory. A recent strategy developed by J. Colombeau culminates with multiplication and integration theory for distributions. This paper develops this theory in the spirit of a sequence approach, much like fundamental sequences are to distributions. However, in the new tempered distribution theory the sequences can be noncountable. T. Todorov developed these techniques for new distributions. However, since so many applications require Fourier analysis, the new tempered distributions provide a natural setting for physics and signal analysis. The paper illustrates the product of two Dirac delta functionals,(x)(x). Other nonregular distributional products can also be computed in the same manner. The paper culminates with a new application of annihilation and creation operators in quantum field theory. 相似文献
985.
采用微核检测技术,研究了亚硒酸钠对启东肝癌高发区不同类型饮用水诱发健康人外周血淋巴细胞微核的拮抗作用。结果表明:(1)各实验水体对细胞的毒性作用,宅沟水〉泯沟水〉自来水〉双蒸水。微核率随着实验水体剂量的增加而升高;(2)1mg/L的亚硒酸钠浓度对泯沟水,自来水诱发的微核效应有是显的抑制和/或拮抗作用,呈现明显的剂量-效应关系,提示肝癌高发区饮用水体中确存在与肝癌发病相关的致畸因子,补硒确有防与治原 相似文献
986.
Kaul N Agrawal H Maske P Rao JR Mahadik KR Kadam SS 《Journal of separation science》2005,28(13):1566-1576
Two sensitive and reproducible methods are described for the quantitative determination of itopride hydrochloride (IH) in the presence of its degradation products. The first method is based on HPLC separation on a reversed phase Kromasil column [C18 (5-microm, 25 cm x 4.6 mm, ID)] at ambient temperature using a mobile phase consisting of methanol and water (70:30, v/v) adjusted to pH 4.0 with orthophosphoric acid with UV detection at 258 nm. The flow rate was 1.0 mL per min with an average operating pressure of 180 kg/cm2. The second method is based on HPTLC separation on silica gel 60 F254 using toluene:methanol:chloroform:10% ammonia (5.0:3.0:6.0:0.1, v/v/v/v) as mobile phase at 270 nm. The analysis of variance (ANOVA) and Student's t-test were applied to correlate the results of IH determination in dosage form by means of HPLC and HPTLC methods. The drug was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment, UV, and photodegradation. The proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline, and oxidative degradation processes at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. In addition the pH-rate profile of degradation of IH in constant ionic strength buffer solutions in the pH range 2-11 was studied. 相似文献
987.
J. B. Esquivel 《Chromatographia》1988,26(1):321-323
Summary Wavelength accuracy is an important factor of LC detection which can have serious effects on detector response, analytical results, and inter-laboratory reproducibility. Current wavelength accuracy test procedures for LC detectors have serious limitations or are very elaborate. This paper describes two new test procedures which employ Tb+3 and Er+3 solutions, these ions have narrow well defined absorption bands, and provide suitable test points throughout the ultraviolet-visible spectrum. These new test methods are fast, simple, applicable to any detector, and cover the spectral regions most frequently employed in LC detection. 相似文献
988.
I. Mäkinen Anna-Mari Suortti Seppo Pönni Sami Huhtala 《Accreditation and quality assurance》2002,7(5):209-213
Mineral oil products are abundant sources of environmental contamination. A Finnishproficiency test was carried out to investigate
the quality of data provided in an analysis of mineral oil in polluted soils. The homogeneity and stability of the samples
were tested. The calculated concentration or the median value of the results was used as the assigned value because of the
unavailability of certified reference materials (CRMs). The samples were analysed using an infrared spectroscopy (IR) or gas
chromatography (GC) procedure. Even if the participating laboratories had little experience with GC, the results were promising.
Hence, the GC procedure will replace IR as the new ISO standard (ISO/DIS 16703) in the near future in many Finnish environmental
laboratories. There is a need for CRMs for the determination of mineral oil using the GC method due to common contamination
problems caused by mineral oil.
Received: 9 December 2001 Accepted: 14 February 2002 相似文献
989.
990.
Two compounds are described with interesting properties for use in DSC. The first compound is adamantane (C10H16), with a reversible solid-solid transition at 208.62 K [1], suitable for DSC calibration at this low temperature [2]. The second compound is 4,4'-azoxyanisole (C14H14N2O3), with a liquid crystal range between 390 and 407 K [3]. This compound shows two transitions on heating, with a large heat effect at 390 K and a small heat effect at 407 K. For this reason, this substance is well suitable for testing the sensitivity and the resolution of DSC instruments [4]. For both compounds not only the heating, but also the cooling behaviour is investigated.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献